-77.98% is the change from 999 to 220
Calculation steps:
[( 220 - 999 ) ÷ 999] x 100 = -77.98%
Formula
Percentage change = [(220 - 999) / 999] x 100
Subtract the new number by the original number
220 - 999 = -779
-779 ÷ 999 = -0.7797797797797797
-0.7797797797797797 x 100 = -77.98%